| Yakara plc | Edinburgh |
| Yammayap Ltd | Dorset |
| Yammer Web Design | West Yorkshire |
| YapCRM Ltd | Staffordshire |
| Yaqrit Discovery Ltd | |
| Yaser UK | |
| Yaudience | |
| YCR Distribution | West Yorkshire |
| Yeap Digital | Edinburgh |
| Yello Media Ltd | Lincolnshire |
| Yello Studio Ltd | Devon |
| Yellow Circle | Staffordshire |
| Yellow Duck Web Design | Essex |
| Yellow Marshmallow Group Ltd | Shropshire |
| Yellow Moose | Buckinghamshire |
| Yellow Mouse Studios Ltd | |
| Yellowbox | |
| YellowDog | Bristol |
| Yellowgrid | Greater Manchester |
| Yellowphin Ltd | Lancashire |
| Yellowstone | Bedfordshire |
| Yeovil Circuits Ltd | Somerset |
| Yepic AI Ltd | |
| Yes Computers & IT | West Midlands |
| Yes Creative | Hampshire |
| Yes We Do Websites | |
| YesNo | |
| Yetiserve Computer Services | Cornwall |
| YFM Private Equity Ltd | |
| Yfood | Greater London |
| YLD Ltd | |
| YNH Ltd | Lancashire |
| Yo Telecom Ltd | |
| Yo Wireless Global Ltd | |
| Yobitel Communications Ltd | East Sussex |
| Yodel Delivery Network Ltd | |
| Yodel Mobile | |
| Yogi Communications | |
| Yoke | Bristol |
| Yonder Consulting Ltd | |
| YoNET | Kent |
| Yoomee | South Yorkshire |
| York AV Ltd | North Yorkshire |
| York Bioanalytical Solutions | |
| York Data Services | |
| York Interweb | North Yorkshire |
| York IT Services (UK) Ltd | North Yorkshire |
| York St John University | |
| York UK Hosting Ltd | West Midlands |
| Yorkshire Bank | West Yorkshire |